1. Field of the Invention
The present invention relates to the field of dental prophylaxis and more specifically to new prophylactic cleaning and polishing agents and to the formation and utilization of prophylactic preparations incorporating such cleaning and polishing agents. In particular, the invention relates to prophylaxis paste cleaning and polishing compositions comprising selected mineral particles which are thermally processed.
These dental prophylaxis paste compositions have the ability to impart a smooth, highly polished surface to tooth enamel and to effectively remove all types of exogenous stains and accumulations from the teeth without resulting in undue abrasion of the enamel, dentin, or cementum. These compositions serve to clean and polish dental hard tissue in a novel manner such that reaccumulations of dental plaque and pellicle and occurrence and reformation of dental calculus on oral hard tissue are markedly reduced, thereby, significantly reducing the incidence of gingivitis and periodontal disease. Additionally, as a means of contributing to the partial control of dental caries, effective fluoride anticariogenic adjuvants, such as sodium fluoride, stannous fluoride, sodium monofluorophosphate, or acidulated phosphate fluoride, may be incorporated in such compositions. Other anticariogenic agents, such as aluminum carboxylates (U.S. Pat. Nos. 4,042,680 and 4,108,981), may also be advantageously employed in such compositions.
2. Description of the Prior Art
Dental research has developed substantial evidence that beyond the age of thirty years the loss of teeth is predominantly the result of periodontal involvement rather than dental caries. However, evidence in the dental literature indicates that gingivitis may be present in a large portion of the population as early as six to eight years of age. In this form, the disease is reversible. A major factor contributing to periodontal disease is the accumulation of certain forms of dental plaque and calculus on the teeth. These accumulations result in tissue inflammation of the surrounding gingiva, and, as the condition increases in severity, the periodontal fibers and supporting bone subsequently become affected. These reactions lead to the destruction of the supporting structures and the subsequent mass loss, in most instances, of sound teeth.
In the past, prophylaxis pastes have been used for the removal of exogenous stains that could not be removed by the routine use of a dentifrice and toothbrush, and other considerations, such as polishing ability, abrasiveness, and fluoride therapy, were regarded as secondary. Even at the present, many widely used dental prophylaxis products contain pumice, silica, or other hard materials of a relatively large particle size in order to achieve fast and thorough cleaning. It is apparent that excessive abrasion and scratching of the enamel increase the rate of reformation of exogenous stains and produce a low degree of enamel polish. It has been shown in several studies that a smooth, highly polished tooth surface is less receptive to reformation and retention of plaque, exogenous debris, pellicle, stains, and dental calculus.
Various abrasives have been employed for dental prophylactic treatment, but most appear to have significant disadvantages, both for the patient and the dentist or dental hygienist. For example, many are quite abrasive, some do not clean satisfactorily; the majority are inadequate polishing agents; and most, from a therapeutic viewpoint, have little, if any, supporting laboratory and clinical data demonstrating their effectiveness. Moreover, some products contain abrasives of high physical hardness and very low particle size that accelerate the normal attrition of the dental handpiece.
There are two essential characteristics that an improved abrasive system for use in a dental prophylaxis paste must possess in order to attain the desired properties. The first characteristic is the physical nature of the compound and how it relates to the physical functions of polishing, cleaning, abrasion, and scratching of the oral hard tissue. The relationship between cleaning, polishing, abrasion, and scratching induced by an abrasive agent is complex, and is dependent on a variety of properties of the abrasive: for example, chemical composition, crystal structure, cleavage, friability, hardness, particle shape, particle surface features, and particle size distribution. Obviously, high cleaning ability and low abrasion ae diametric opposites, as are high cleaning and high polishing. Thus, it is inevitable that some concessions must be made to achieve a suitable compromise, a fact that accounts for the large differences in cleaning, polishing, and abrasion of the various abrasives used in commercial prophylaxis pastes. The second characteristic is the chemical reactivity of the abrasive compound with fluoride adjuvants. Preferably, the abrasive should be chemically inert to fluoride (and stannous ion) in that the stability and therapeutic efficacy of different fluoride compounds are very dependent on the abrasive since it is the major component of any prophylaxis paste formulation. Fluoride is quite reactive and, depending on the particular abrasive compound, can react not only directly, as in addition and substitution reactions, but can be readily adsorbed onto the surface of the abrasive particles by electrostatic forces or can be associated with the surface in the form of a complex with a metal atom in the crystal lattice of the abrasive.
Although significant improvements in the polishing efficacy of prophylaxis compositions have been achieved in recent years through the use of zirconium silicate (U.S. Pat. Nos. 3,330,732 and 3,378,445), alumina (U.S. Pat. No. 3,670,076), and feldspar (U.S. Pat. No. 3,892,843), these agents still fall short of imparting maximum levels of polish during a typical, short prophylaxis treatment. Additionally, in order to achieve good cleaning properties with these materials, large particles are necessary; however, such particle sizes cause undesirably high abrasiveness an do not polish well. To obtain polishing, especially with alumina or zirconium silicate, it is necessary to include small-sized particles, which have little cleaning effect.
The beneficial effects, in terms of a reduction in the incidence of dental caries, resulting from the incorporation of water-soluble fluoride salts, such as sodium fluoride, stannous fluoride, sodium monofluorophosphate, or acidulated phosphate fluoride, are well known. However, efforts to utilize such salts in prophylaxis paste compositions have been handicapped by the tendency of fluoride and/or tin(II) ions to be inactivated and rendered unavailable by other ingredients, particularly the abrasive component of such compositions. In general, while prophylactic abrasives in therapeutic products used today are to varying degrees compatible with fluoride agents, there is a wide variation in compatibility. Abrasives containing polyvalent cations such as calcium and iron, either in their crystal structure or as impurities, are usually not particularly compatible.
Thus, prior art materials intended for use as cleaning and polishing constituents of prophylactic compositions have been unsatisfactory in one or more of the following respects, namely poor cleaning and polishing performances (especially with respect to inhibition of reaccumulation of dental calculus, pellicle, plaque, and exogenous stains), incompatibility with fluoride-containing anticariogenic agents, and adverse scratching and abrasion.